One other male worker with minor injuries was taken to a hospital.
Dispatchers received reports that up to a dozen workers were inside when a 60-foot-section came crashing down around noon.
Because it wasn't clear how many people were actually in the building, Dawson said the search would continue through the night.
"We're to going to continue to search throughout the building until we're confident we've looked everywhere someone could be," Dawson said.
Emergency workers were attempting to stabilize the rubble. They brought in sound-sensitive equipment to detect any movements in the collapsed building while they attempt to shore it up. Some rescuers asked people on the scene to be quiet so they could listen to see if any noises were coming from the building.
Robin Kuhn, owner of Old Time Concrete, said his company poured the foundation and footings for building, which was nearly 80 percent complete.
Kuhn said his workers were scheduled to be at the site around the time of the collapse but were not there because they were working on the other side.
"I have a God that put us in the right place at the right time," Kuhn said.
Cindy Martin, who works across the street at Cotas Barber Shop, said she heard a loud noise and saw the building come down and people running out.
"It's only the grace of God them other guys got out," Martin said.
It wasn't clear what caused the collapse. The two-story wood structure is part of Chester Village Green, a mixed used development in Chester. The community is about 15 miles south of Richmond.